Game Development Community

Culling problems...

by Symbols · in Artist Corner · 02/07/2005 (3:38 pm) · 6 replies

Here is a link to an image to explain my problem...

As you will see it is more like front-face culling instead of backface culling...will reversing normals fix this?

http://members.lycos.co.uk/symbols/images/cullprob.jpg

I've fixed scaling and units sizes since this image to correspond with the tree.max file.

I seem to be getting culling problems in TST and I dont know how to solve it.

2-sided in texture is checked.
2-sided in DTS exporter is checked.

Perhaps my scaling is wrong.. but Ive tried resizing and still get the same problem...

Can anyone help.?
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Associate Logan Foster
perPixel Studios
#1
02/08/2005 (12:41 pm)
Looks like your normals are being flipped. The easiest solution is to add a normal modifier to your object and force them to be unified.

As for what causes this: Whenever you use a mirror operation in any 3D application the app applies an inverse scale to the object (ie. -100% instead of the 100% it was before mirroring). This inverse scale is read properly when displayed in the 3D app but not when the data is exported. This is because the winding for the faces is now backwards and is read as such by exporter plugins.

Logan

Torque Owner Symbols
#2
02/09/2005 (3:29 am)
.....

Torque Owner Symbols
#3
02/09/2005 (4:25 am)
Yes, I used symmetry tools to make the model... Ive managed to get it working a lot better now thanks to your help.

I unified the normals but I still seem to be getting weird problems... parts of the model are still acting like they are being culled in the sense that if something is behind the nearest face to your camera/view, the behind face is shown....

This is more like frontface culling...

I made a duplicate of the helmet, flipping the normals of the copy, and this helped too, but still wasnt perfect..

I tried making a models using no symmetry/mirror methods and there is still problems even after meesing about with the normals. I've liitle more to ask/say.. I'm annoyed at how much I've tried and tested and need a big rest to the disadvatage of development.

I am willing to supply a link to the file soon, so that someone out there can help.

Associate Logan Foster
perPixel Studios
#4
02/09/2005 (8:38 am)
Email it over and I will try to take a look tomorrow night.

Edit: Have you tried the box trick method yet?

Torque Owner Symbols
#5
02/09/2005 (9:58 am)
I've sussed out that when I creat polygons clockwise/anti-clockwise, this affects how the polys are culled, though Ive had to make two copies of the model and flip the normals for one of them... ideally thought, I only want one model and perhaps some coding that would disable 'culling' for this object..

Other than that it seems to be fine now.

Associate Logan Foster
perPixel Studios
#6
02/10/2005 (8:09 am)
The error that you are encountering has nothing to do with backface or frontface culling and has everything to do with the winding of the normals from the model you created in Max. You do not need to use the method that you are using, just fix the winding and ensure that you dont have a negative scale still applied.

Logan